how to drill and tap? (1 Viewer)

[semlin]

need some advice on drilling and tapping if anyone can help.

i have three nasty broken rusted bolt stubs in my frame after taking off my tow hitch. I tried a drill out on one and there is no way. the rust is ridiculous and a little scary. It is so bad I am not sure I can use my tow hitch again because the mounting holes on the hitch have just rusted away.

I think I have to drill these out and re-tap. The question is how to do this. I have never drilled out a bolt before and these are pretty big (i think at least 12mm) and extend inside the frame beyond the captive nut probably a good ½" at least. I can see it taking hours. Is it just a matter of using gradually larger drill bits or is there some way to get the remnants of the bolt out once you get a big enough hole? also, am I at risk of breaking the weld on the captive nuts inside the frame?

also,

What kind of drill bit is best?

is it worth getting a cheap tap and die set to tap out a new bolt? I can pick one up for $50 or should I just go to a shop and get them to do it.

thanks for any help

 

[Kofoed]

You can try and drilll out the center of the bolt then use an easy-out. In conjunction, use the hot wrench around the bolt hole to help free it. Use plenty of penetrating oil. Heating and easy out may have to be done a number of times before success.

 

[semlin]

sorry, i meant to say I tried pntrating oil and a propane torch as well. there is enough of a nub to grab with vice grips but even after heating the bolt for 5 minutes and putting an extension arm on the vice grips, nada. they are stuck fast.

 

[pound3151]

Try soaking w/penetrating oil for a few days. Then start with a small drill bit up the center of the bolt. When you get a whole up the center, increase the size of your drill bit but don't exceed the outer limits of the bolt if you want to reuse the same threads. Then try a good easy out. I have my tow hitch bolts tapped out to 1/2" with stainless steel bolts. 1/2" is just a bit larger than the stock size.

 

[Cube Dweller]

Propane won't get it hot enough to make much of a difference. Find someone with oxy-acetelyne and get it very hot, concentrating the heat on the captive nut if possible. Twist what's left of the bolt while it's still glowing.

Another option are reverse twist drill bits. As you drill out the bolt using a bit close in diameter to the minor diameter of the bolt thread, sometimes the bolt will back out.

 

[VTFJ40]

Skip the easy out. I've still a snapped one in my rear crossmember. You'll waste drill bits tryin to drill one of those out.

 

[cheap 40]

Easy outs suck because most of them are tapered, and as you try to twist the bolt out, all it does is wedge the bolt in the threads even more. If you have a nub left, you may be able to weld a nut or another bolt to it so that you have something to get a wrench on. I would suggest a rather liberal application of heat, penetrating oil, and maybe a BFH. When everything is heated up, you can knock some of the crap (rust) loose inside the threads and allow the oil to actually work into the threads. I recently installed a hitch on my 97 and was thinking about what a pain it would be to have one of those bolts break off. Also, you can try drilling the center of the bolt out before the aforementioned application of heat, oil, and BFH. The hole will allow the bolt room to shrink down and possibly work loose in the threads.

And it may take time.........don't get in a hurry or you may fubar what you have left to work with. Hope that haelps some.

Tony

 

[flintknapper]

Semlin,

My experience with large bolts that are rusty is that no amount of penetrating oil is of any benefit. The bond between the bolt and the treads on the captive nut is one of pure rust. Heating won't hurt but I don't do it until I'm ready to remove the bolt after having drilled it.

My suggestion, is to use increasingly larger bits to drill out the center until there is only the threads and a small amount of material left. At this point heating becomes effective and the use of a non tapered E-Z out or reverse spiral drill bit may do the trick. If not... take a punch 90 deg. to the stub that is left and see if you can punch it in towards the center of the hole.

Once you get the rust bond broken you're home free. Don't buy an entire tap set unless you just want to have it around. Individual taps are available, as well as the handles.

Good luck.

 

[KLF]

Some of you guys need to come spend some time in the rust-belt.

Do NOT use an EZ-Out. You will end up with the broken off tip in your frame, and no way to get it out. They are really only meant for removing hardware bit that have broken off due to over-tightening. I have never seen one work at getting out a rusty bolt remnant, but I have seen several of them snap off.

semlin: get some GOOD SHARP drill bits, carefully center-punch the middle of the busted off bolt, start small (approx 3/16"), drill a pilot as close to the center as you can. Then work your way up. Use lots of lubricant or tapping fluid. If you're really luck, the heat from drilling will break the stub free from the rusted threads, but not likely.

Get a GOOD tap, a cheap one will just go dull with the rust and might even break.

 

[e9999]

if you have a good stub left, you could try the newer bolt removers that fit around the stub. No drilling needed. Sears has them cheap. Handy to have anyway. Try with impact wrench maybe even better?

and sometimes wacking the bolt will loosen things up too.

 

[spressomon]

More than likely the corroded bolt has essentially become "one" with the capture nut. I had the same thing happen on my rr sway arm bracket on my 100. I drilled it out to the tap-drill diameter and ran the tap creating new threads. Worst case you go to the next SAE size tap/bolt size. FYI: My bolt size was 8mmx1.25...I drilled and tapped to 9mmx1.25...only to discover they don't make 9mmx1.25 bolts...only taps & dies! How stupid is that? I ened up making my own 9mmx1.25 bolt with the same size die!

 

[honk]

If you have an oxy/acetyline torch set use the cutting head. Put heat right to the center of the rusty broken bolt until it's red hot then blast the bolt out by squeezing the oxygen handle with the flame aimed right into the cener of the bolt just like if you were cutting steel. The errant bolt remains will disapear and if you've done this carefully the original threads will still be there for you to clean up with a tap.

 

[Radd Cruisers]

If you have an oxy/acetyline torch set use the cutting head. Put heat right to the center of the rusty broken bolt until it's red hot then blast the bolt out by squeezing the oxygen handle with the flame aimed right into the cener of the bolt just like if you were cutting steel. The errant bolt remains will disapear and if you've done this carefully the original threads will still be there for you to clean up with a tap.

Hmmmmm, never tried that before.


If its not a hidden nut inside the frame, meaning accessable I will just knock it through the frame and put a nut on the backside.

In most cases its just not worth the time and effort.

Rob

 

[Bryan E.]

Don't waste your money on a cheap tap set or drill bits. Better to get a couple of really high quality drill bits and then a couple of high quality taps. A distributor to machine shops will have a good selection. You won't believe how much faster and better a high performance drill and tap will cut. Could be the difference of this won't work vs. it went through like butter. Something we see daily in my work as a machinist, even though we want to spend as little as possible on tooling for the job, better tools makes some jobs look easy. You will be drilling a hardened bolt so you will want at least a really good cobalt drill. I recommend using a centerdrill first to start the hole. A good cobalt drill might work fine, but if it doesn't start cutting immediatly, don't let it wear and wear as it will harden the surface of the hole your drilling. You can try something like a 1/8" drill first then go to a larger drill. Going to a 3/8" then to a 1/2" doesn't work well though so you might try one small drill to use to guide your larger drill on center, then go for a tap size drill for what every tap sized hole your working on. When taping, use good taping oil, go forward a little like 3/4 of a turn, then back up a 1/4 turn, forward 3/4 turn and so on. Not a fun project but take your time and do it right.

Good Luck

 

[semlin]

well i bought a cobalt set for metal drilling and spent an hour using 1/8" or so bits and got about an inch drilled on one bolt. sadly the bits are crap. used lots of tapping fluid. the only way they drilled was to press hard. i may have to give in and find someone and pay them.

 

[Bryan E.]

Semlin.............Call a supply house, or search on the net and get some high performance drills. They won't be as expensive as having this done for you, but might be $5-10 each. I am talking about drills for heat treated steel, or for drilling Inconel. I'm not at work, so can't give you the exact names of drills I'm talking about, but they make the impossible, possible. I'll posts again tomorrow and try to give you some names of drills and where to order it.

 

[Tigerstripe40]

I am going to second (or third) NOT using an "EZ Out"...

The first (and last) time I used one, I snapped it off in my engine block.. I had to take the truck to DJ's Traction Systems where they had to sit on the bolt with an Oxy-acetalene torch to retemper the steel, then they were able to drill it out...

Long story short, it was $267 that I never want to spend again....
When I got home I tossed the EZ-outs into the trash.

Now, any time I take a bolt off I soak it with PB Blaster and when I put stuff back together I use Antisieze...

HTH.

 

[Bryan E.]

Semlin, Looks like a really good quality Cobalt drill should work for this application. Go to a 5/16" if your tap size will allow it. It's going to be a lot tougher than a 1/8". Use some cutting fluid and a slow drill rpm speed. If your drill isn't varible speed, just start and stop, not letting it rap up to high speed. Make sure you are cutting, good pressure, chips coming out of the hole or a nice spirol. If it stops cutting, get off of it in a hurry, cause it will work harden the surface of the hole. IF it stops cutting, get another drill that sharp and go again. You should be able to tell when it gets dull. You should be able to do this with a regular high quality*(NOT CHINA or Tiawon, but use American or German, etc) Cobalt drill. Use the shortest drill possible. We use Titex drills that are a high performance drill but I consulted several guys here at work and we agree that you probably don't need anything more than Cobalt. Drill out the hole to tap size, then re-tap with high quality tap.
Good Luck,

 

[JRFJ4-]

Oxy/Acetylene

Try to heat the broken bolt up cherry red, then let it cool completely on it's on.

The broken bolt will come out with your fingers. Somehow about the expanding and contracting loosens it up. I've seen this work on a bunch of different parts.

J.R.

 

[Niner]

There are reverse cut drill bits that sometimes will break the bolt loose while drilling (in Reverse). this ususlly works after heating the nut.